1. Technical Field
The disclosure relates to a control system that controls drive torque of a hybrid vehicle including an engine and electric motors, and also relates to a control method, and a hybrid vehicle.
2. Description of Related Art
One example of a hybrid vehicle including an engine and motor-generators as driving force sources is described in Japanese Patent Application Publication No. 2010-215038 (JP 2010-215038 A). In the example of the hybrid vehicle described in JP 2010-215038 A, the engine and a first motor-generator are coupled to a differential mechanism that performs differential operation with three rotational elements, and an output element of the differential mechanism is coupled to an input element of a front-and-rear-wheel driving force distribution mechanism in the form of a planetary gear mechanism, for example. The front-and-rear-wheel driving force distribution mechanism has two rotational elements that provide output elements, other than the input element, and is arranged to deliver driving force from one of the output elements to the front wheels, and deliver driving force from the other output element to the rear wheels. A second motor-generator is coupled to the output element that delivers driving force to the rear wheels. Then, a clutch is provided for coupling these two output elements or disconnecting the output elements from each other.
When the engine is started from a condition where the vehicle is traveling with the engine stopped, the engine is motored by the first motor-generator. In this case, reaction-force torque is applied to the output element of the differential mechanism. Thus, in the system described in JP 2010-215038 A, the clutch is engaged so as to couple the two rotational elements of the front-and-rear-wheel driving force distribution mechanism, and integrate all components of the front-and-rear-wheel driving force distribution mechanism. When the clutch is engaged, the front wheels and the rear wheels cannot rotate at differential speeds. Therefore, in the system described in JP 2010-215038 A, the engine is inhibited from being started during turning.